A USDA hardiness zone is a geographically-defined zone in which a specific category of plant life is capable of growing, as defined by temperature hardiness, or ability to withstand the minimum temperatures of the zone. The zones were first developed by the United States Department of Agriculture (USDA), and have subsequently been adopted elsewhere. They are categorized according to the mean of the lowest temperature recorded each winter, termed the "average annual minimum temperature". Thus if five successive winters reach respective minima of −14 °C, −12 °C, −8 °C, −16 °C, and −13 °C, the mean coldest temperature is −12.6 °C, placing the site in zone 7. (from Wikipedia).
One has to be carefull with these zones. There are many more factors that rule the regions where a plant can survive, like humidity, rainfall, length of the low temperatures (10 minutes or 10 hours), the maximum temps that day, the length of the winter, ..., add to that the microclimate of your garden , the fitness of the plant (is in in a pot or in the soil, is it sick or healty, is it a seedling or a 10 year old mature plant, ...). But its far better than having nothing.
Here you can find the European hardiness zones.
I've
read in this article that Ensete glaucum is less hardy than Ensete ventricosum. I've destilled my "plants wanted" list from this article.